Yes you can just pull the sim out of your current phone and insert it in the new phone and it will work, that's all you need to do!
How do I switch my MetroPCS service to another phone?
With them, if you want to move your phone number and service over to a new device, you must first put a MetroPCS SIM card in the new phone. Next, you'll need to go through their activation process. You can either do this through a MetroPCS store, or you can do it online, whichever is more convenient for you.