Zaha is on-loan at Palace after signing for United in January.
Pearce said: "I have to bear in mind that a lot has happened to Wilf in a short space of time.
"He's still one of the younger boys but he seems happy. I'm seeing the same kid as I did a couple of months ago.
"I think Wilf is one of those nice, easy-going lads and not much worries him. Whether he's gone to United or stayed at Palace I'll view him as the same player who's learning, maturing and will get better and better. We asked Wilf to play centre forward [against Sweden] last month rather than his wide position and we might do that again."