@rocketraman,

It would greatly depend on how the plug fails. There is a setting that will allow you to set what happens when the plug loses power and receives power again: On, Off, Last 'On' State

For capacity, the device is only rated for 15A, 1800W under a general resistive load, however a sump pump is an inductive load appliance. It is only recommended to make sure that the pump is only using 1/6 of the devices max capacity in this case and is usually limited to 1/2 HP motors.

Take a look at this article on the capacities of plugs, even though it relates to lighting and plugs: How Much is Too Much? Outdoor Smart Plug Capacities