Around what age do boys stop wrestling, etc with friends?

It depends on their maturity level and when they realize that physical dominance doesn't dictate the pecking order any more. I know of some that do continue ito their 20's if not older. I also know some that figure it out by 9th or 10th grade. It is a maturity step and you were right to attempt to teach your son how to control those impulses. The sooner they do the sooner they start using their heads to solve issues as opposed to violence or the threat of it. It is part of what boys do but it is also just another developmental step they need to work through with help at times.