Record signing Bent was axed from the starting line-up against the Baggies, with Lambert preferring Gabriel Agbonlahor and Christian Benteke in his starting line-up.
Bent was introduced midway through the second half and earned Villa a point with an 80th-minute close-range effort.
The England striker admitted it has been a difficult couple of weeks having also lost his England spot and the Villa captaincy, to Ron Vlaar.
But, when asked if Bent was upset, Lambert said: "No, he was great. There was no problem. I just named the team and that's the team I picked.
"It was a world-class substitution! I need everyone, it's a collective thing, I never look at individuals. The goal was brilliant, it was a world-class finish.
"He was fine at full-time. I spoke to him in the dressing room as well. He was totally fine, totally, no problem, none."
Lambert added: "Everyone is as important as anyone else. I explained the captaincy thing was to do (let him focus on) what he did there - to score. That's the only reason I did it.
"I need everyone. If we can keep the collective thing and have the crowd with us, we'll be fine."
Lambert was full of praise for the way his players responded to going behind to a Shane Long goal, particularly after playing 120 minutes against Manchester City in the Capital One Cup in midweek.
Watch: Bent rescues point for Aston Villa... More Videos
He said: "I think it was harsh going behind, especially after the first half.
"The goalkeeper (Ben Foster) has made two world-class saves and when you go behind, especially in a derby, it puts you on the back foot.
"I thought the response was great, especially after playing 120 minutes on Tuesday. It was a big, big ask but the response was excellent."
Baggies boss Steve Clarke was disappointed to concede a late goal but hailed a top-drawer performance from Foster.
The former England player bounced back from his poor performance against Liverpool in midweek with several fine saves.
Clarke said: "Having been in that position I'm a little bit disappointed we didn't go on and win it.
"Obviously, in an away game like this you probably need the second goal just to alleviate a little bit of the late pressure you know is going to come when the ball is going to be in your box a lot.
"But Ben Foster was excellent. I said the other night when he made the mistakes there was nothing to worry about - and he proved that today.
"He's a top goalkeeper and made one save in the first half off the deflected shot which was unbelievable, fantastic.
"You need your goalkeeper to make saves in the Premier League to help you get the points. He's up there with the best of them.
"Compared to some of the other keepers I've worked with Ben may be a little more unorthodox - but he makes the saves just the same.
"I've only known him for 12 weeks but he's been really good for us."
Albion will assess the extent of injuries to skipper Chris Brunt (hamstring) and defender Billy Jones (knee) during the next few days.