Pool pump 20amp AC motor - significant inductive arcing when shutting off
You need a motor contactor rated for 1-1/2 or 2 Hp. Use a timer to turn the contactor on and off. A timer rated for the contactor coil current should be much less expensive. MOVs are really designed for occasional high voltage spikes. They are not a substitute for a properly rated contactor.

Here are a couple of contactor examples:

https://www.grainger.com/product/EATON-120VAC-Definite-Purpose-Contactor-49C067

https://www.grainger.com/product/DAYTON-120VAC-Definite-Purpose-Contactor-6GNY9

Note that these are 2-pole contractors that will open both power lines simultaneously.