From a technical standpoint, yes. Here is the substitution you can make:
A Medium Duty pressure switch can be used in place of a Standard Duty pressure switch.
Medium Duty pressure switches can handle higher HP (horsepower) pumps, so they can be used as a Standard Duty switch without an issues. The contacts may even last longer on them when running a lower HP pump.
However - You can ABSOLUTELY NOT do the opposite! Never substitute a "Standard Duty" pressure switch in an application that requires "Medium Duty" switch.
