300.6 Protection Against Corrosion.
Metal raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes, cable sheathing, cabinets, elbows, couplings, fittings, supports, and support hardware shall be of materials suitable for the environment in which they are to be installed.
I am not a fan of exposed PVC but in this location I would certainly consider it.
If this is a high chlorine area it is about the only thing that will last.
Proper ventilation of pool pump rooms is the only way steel equipment will last.