Not sure why we would use any such thing for a torpedo, you'd need a rocket motor to compensate for the lack of water touching the propeller (like on the Russian Skval), same with a ship's screw and prop. How will you move a propeller though the water if said propeller doesn't touch the water thanks to the water-repellent properties of this material (you could use a pump-jet to compensate, but then this material wouldn't be needed, unless to coat the bottom of the ship to decrease friction)!!! You'll not be able to displace enough water to achieve propulsion without having the prop actually touch and push the water away. You'd be going nowhere otherwise. Fast torpedoes don't interest a USN that is interested in control-ability, not speed. Too hard to maneuver, redirect or terminate the attack pattern of a high-speed system and good luck reprogramming it to attack another higher-priority target mid-run, something slower torpedoes can do. Yes, China does have a concept for a high-speed submarine using water-repellent lubrication and rocket motors, but that's dangerous, noisy and represents an engineering challenge that is unnecessary.
You could use this material for a hydroplane/hydrofoil, to decrease the amount of friction imparted upon it by the water, but these types of crafts are already dangerous at high-speeds and prone to going airborne, further decreasing the friction imparted upon them would increase their speeds and thus probability of being involved in an accident.
For electronics, no, we don't need it either as these are compartmentalized within a system and shouldn't be exposed unless said system is actively exploding.
For Helo-rotors, ship decks, aircraft and missile skins, and exposed radars, yes
@Peter C is right and this could cut down on maintenance costs and prolong the lifespan of the system by reducing water-induced corrosion. But that's about it.
@Gufi - here's your answer.