Can you post pics of the entire pump? You posted a pic of the motor but the same motor is used on many pumps. Are there any markings or labels on the pump?
If that is a crack then you need to replace the pump. A product like flexseal is not going to hold back water under pressure.
Took a second look, and this was the solution, it was a piece of pipe glued there. Took it out and there were threads. Just re-piped the whole thing and its working like new. Thanks!Carefully put ur finger in and feel under to see if theres threads and that piece screws in. If it's part of the welded body then its done