Since the pump house is a "detached" structure, the pump house panel should have a local ground rod for lightning protection. Ground and neutral should remain separated.

The number of breakers determine whether or not it needs a main breaker. Memory says 6.

Panels are divided into two major categories "main lug" or "main breaker". "main lug" is wired for separated N and ground. "Main breaker" has a "main breaker" and the N and G are bonded together.

Usually there is a way to unbond the neutral and you purchase a ground bar kit to add to the panel. This gives you the separate G and N connections and a disconnect for that sub-panel.

You can read the NEC for free online.