what are the parts you are painting there made from?

In my experience aluminium doesn't massively like to be painted... generally found results were lacking unless an etch primer was used.

Needless to say, regardless of the metal type you need to be meticulous about degreasing first too. A good soak and scrub in hot water with either some proper degreaser or washing up liquid will help a lot with getting a lasting finish.

What parts are you worried about wear on? Mating surfaces shouldn't be moving really once assembled so I wouldn't be overly concerned about wear and tear on them.