[BrianG]

Aside from water and contaminants from wrecking the motor bearings or rusting the motor shaft, I don't see why the motor would care if it got a little wet. The wires are electrically insulated up to the tip where you solder. Even without that, water has high enough resistance to not make it a factor.

However, the ESC is different. Even with the water-resistance coating, I'd avoid water. Despite water having high resistance, the low-level signals in the brain circuits may be affected and cause all sorts of havoc. If you don't care about the warranty, you could take the case off, make a new sealed case with just the wires and heatsink poking out. Then you can use silicone or shoe-goo to seal the edges if the wires and HS.