The parts that are silver is the aluminum...so it's just the color of the bare aluminum, so that won't corrode or fade or wear off.
The black circle on the front is just black plastic, so that won't wear either.
They should be fine!
* Takes ~2-3 weeks to get them here when purhchased, FYI.
Daily: Audi S4 b5 | Project: Turbo ZX3
LED Conversions | Vinyl Carbon Wrapping | Powdercoated Valve Covers