...will be using a 2hp pump, and it draws 12A... Was looking mostly for 15A rating so it wouldn't be at max rating.
That's just the running amps, you're missing what it requires at start which could be more than 60 amps. IMO, this is NOT an application for solid state relays.
It looks like you are in the US so yes, phase wires going to the pump must be switched, they are each 120vac to ground. It is required by code and as a benefit, it lessens the chances of relay contacts welding and the pump staying on. Does your overpressure device dump the water in a drain or all over the floor somewhere? Most are right at the tank and if it vents, it will go everywhere... at pressure!
I've had a pair of these running a 1hp pump, 240 feet down, running for several years without issue. There is a 100psi transducer feeding an UNO for control.
While I built the system for winter related well freezing issues (story for another day), the side benefit is better control of my domestic water system that I could not achieve with a mechanical switch. I have my operating range set to 40psi turn-on/50psi turn-off. This was originally done to provide better shower flow on the second floor but the unforeseen benefit turned out much better hot water generation with a 30 year old oil burner with a summer-winter hot water coil. The increased the pressure increased the hot water efficiency due to the higher pressure in the heat exchanger coil. The net result was that I was able to reduce my boiler firing temperature, saving about 30 gallons of oil a year, roughly a 5% savings. Totally unexpected!
Edit: Just had a scan through eBay looking for Leo's suggestion above. Time to replace what I have with one of the below, it's a far cleaner solution: