Why isn't the switch at the pump? How are you going to get power from the house to the pump, without new a new power line?

After all this confusion - I expect that the OP means to "control" the pump from the house. If I can interpret the issue (risky, always).
a) The house has a back-up generator.
b) The line to the pump is from the house, but the power to the tank is from the shop, not backed up.
c) The pressure switch is at the tank.

I interpret this to mean that a 120V pressure-switch is controlling a 240V pump, powered by two different sources. Which is flat-out nuts.

I am interpreting (again, risky) that the OP wants the controls at the pump.

So, the 120V source at the shop will control a 240V (hopefully) contactor at the pump.

All the while forgetting that if there is a power-failure, that 120V source will be dead - so, no water.

Clue 1: The tank does not care where it is in the system.
Clue 2: The tank will be perfectly happy staying where it is, with all controls, pressure-switch, contactor and so forth at the pump - in suitable enclosures, of course.

Peter Wieck
Melrose Park, PA