The pump should possess protection on a stand-alone basis, and not depend on everything else being just right. Relay controlled pumps are about the worst possible situation. One system component can fail, and the pump won't know about it. The simplest form of protection is a pressure relief valve, but sometimes it's too simple. A lot of pumps chosen for lawn sprinkler use don't operate all that far from their maximum possible pressure (when trying to pump into a closed system, aka "deadheading") and that provides very little range to have a relief valve operate in.
More applicable to low-pressure pumps might be a thermal cutoff. These mount in a pump's drain connection, and react to a dangerous rise in the pump's water temperature, and cut off pump power completely, until the temperature falls back to a safe range.