Remote indicators for sump pump
With the listing on the pump for 15 amp circuit this should be your max. 

There are several ways to monitor if there is power at the outlet. The easiest way would be to install a neon or led indicator light; very low current draw on both with long life spans. There are modules you can put on the hot wire and they activate a switch when the motor is running that could turn on a second neon or led indicator lamp. I have similar setups on some motor controls so I can see at a glance if the breaker is on and if the motor is running. Both could be added to a single gang box attached to your existing outlet box.

The quick Google search I found cr2550 remote current indicator. Pull the black wire through the center of the core and when your pump is running the led will light. Its all wired for 11.85$ max continuous load 20 amps.  (I use accuamp but they cost about 75$  and can handle up to 175 amps with adjustable turn on point). a simple ideal indicator part # 777121 attached to the connections of the outlet black &amp; white will show when there is power (120v) indicator.  If the LED is not lit you know the pump is not running either not enough water or pump has failed if the other indicator is on.

Hope this helps.