When my Doctor and I were discussing what life would be like with my morphine pump, it did not sound half bad. Replacement is not an option unless there is a brand new one out there that both the company who supplied the pump wants you to have or your pump is malfunctioning. What is replaced yearly or once every two years is the battery and that is all. Battery replacement depends on the dose of morphine you are taking and how often the program on your pump is administering the medication. The pump I was to be getting was a Medtronic's pump and the have a terrific site
http://www.medtronic.com/
Here they can answer many of your questions even if the type of pump you are getting is not medtronics. :o) Good Luck!! I wish you the best!
I am not familiar with the pump as far as how often they need replaced but I believe the medication has to refilled every month or so.
Someone will correct mr here if I am wrong and give you the info you need. If not I will find out for you.