Hello Mike, as you indicated, we never received your pump.
Looks like it got lost in the mail somewhere,.
Good to know you recieved the replacement
What your seeing is not "rust", but silicon deposits caused by the sealant.
We only used this sealant on the first 40 units, all others have a gasket or o-ring on the motor case.
Let me know if you have any problems with your new unit
Dave