You have to use a 240v breaker, you cant use two 120v breakers and think of it as adding up to 240v, this is what it sounds like possibly based on the measurements you took at the pump, if you had a reading of 120v on L1 to ground, and 120v on L2 to ground, but 0v on L1 to L2 this would explain 0v
On a 240V breaker, when connected at the motor, doing the same test would show 120V at L1 and ground, 120V at L2 and ground, and most importantly show 240V at L1 and L2.
you cant take two 120V hot wires each connected to there own breaker and get 240V when probing each wire you would get 0V, but each wire tested against ground will show 120V because there 120V circuits, so two hot wires each connected to there own 120v breaker will not equal 240V together.
in order to get a reading off of 2 wires that will show 240V on the meter the 2 wires have to be connected to a 240V breaker
Its not that testing each leg or line independent of the other is wrong, being that they each read 120V, when measured together they both would read 240V, if there on a correct 240V circuit with a 240V breaker. ....if I didn't get 240V on L1 to L2, then I wont get 120V when testing L1 to ground or 120V on L2 to ground on a correct 240V circuit