BLDC motors mostly aren’t affected by water, even in water the resistance of the water is higher than the coil resistance so the electric mostly just stays in the coil. Water definitely accelerates the rate of bearing wear, sometimes tenfold or hundredfold or more.
The thing inside motors which absolutely does not like water, is the sensor assembly. This is where most problems will be.
If you battle harden a motor, you can also waterproof the phase interconnects and the sensor assembly while you’re in there. Thin epoxy is probably my latest favorite chemical for this, maybe West System 650. If you don’t want to do all that, MG Chemicals # 4228 red insulating varnish is pretty good for that.