Not sure on the wells- I have also seen them painted some paint as bottom of wings and fuselage.
But, the issue of the LG legs is a complicated issue. On most modern aircraft, after the invention of the oleo strut, the landing gears contain several hues, and this is an area to do some research. Sometimes the gear leg was left as a casting, which is matt, not shiny. Sometimes it is painted. Originally many land-based planes were left unpainted, but shipboard planes were almost always painted. The colors cover the rainbow, including aluminum paint. This treatment includes the fork or axle assembly, the area below the oleo. The oleo strut was a combination air spring and hydraulic shock absorber. There is a piston, that attaches to the top of the assembly that holds the axle. It is a stainless steel tube, and polished highly, because it goes inside a seal and you want that seal to last and not leak air or hydraulic fluid. As a result, it is very shiny, and can be done with alclad (probably too much work for such a small area), a good gloss silver or chrome, or a little strip of BMF wrapped around the piston.
The lower assembly, below this piston, would be free to turn, and the plane wouldn't track straight, so there is a scissor assembly to allow it to move up and down, but not rotate. This assembly is usually steel with some sort of coating, not chrome, but maybe a lessor material- zinc, cadmium or whatever, or else painted. The treatment of this scissor assembly varies from airplane to airplane. Additionally, there is a brake line that goes from the LG hinge down the strut, with a flexible hose section where the oleo is. It is usually not furnished but is an area you can add if you want to super-detail your model. This hose was most commonly black.
So you see, a landing gear is actually quite a complicated piece of gear (especially as you include the retract mechanism. An important part, too. A navy fighter my company was working on at the time I left for another job (but is still a top line aircraft) had a landing gear that was 30% of the weight of the empty aircraft (not including engines or avionics)!