I suggest not to make use of any prefixes.
Just we can use Sel_User or User_Sel
This will no cause any performance issue as we are not using sp_.
Also it will help us to search the SP if we have a large number of SPs say 500.
If we want to make a change to user details section of our application. all SPs related to a table can be sorted out easily by starting alphabet. from there we can get the select or Get sp