Double-pole 3-way switch exist?
Sorry, a double pole 3-way switch does not exist. You have two options if you want to be compliant.
1) have a set of regular 3-ways switch a contactor that controls the power to the pump
2) have a set of regular 3-ways switch ONE hot leg of the power to the pump. Using this method, the switch no longer satisfies the "form of disconnect" requirement. You would need to have some form of disconnect at the pump (for when you service it) if you only switch one hot leg with your 3-ways. This may either be a cord and plug arrangement, or an actual double pole disconnect of any variety.