Can you become FAA/TC commercial pilot with metal implants in hand?
The simplest way to answer this is to have your friend call an AME in the city they intend on training and ask them if they feel they will pass the required medical for a CPL. AME's are pretty forthcoming about this kind of stuff and they will often give you an idea over the phone if they feel there is a real issue. AME's are also the ONLY people that can definitively answer this question for your friend as they are the only people that can issue medical certificates.
Generally if the desired applicant has no practically limiting factors (in this case full use of their hand) the worst I would foresee needing is a Statement of Demonstrated Ability (SODA) which basically means they can show that they can execute the required actions of a pilot.
Under the Musculoskeletal section of the AME guidelines it states:

(b) No other organic, functional, or structural disease, defect, or
limitation that the Federal Air Surgeon, based on the case history and
appropriate, qualified medical judgment relating to the condition
involved finds

(1) Makes the person unable to safely perform the
duties or exercise the  privileges of the airman certificate applied
for or held; or


(2) May reasonably be expected, for the maximum
duration of the airman medical certificate applied for or held, to
make the person unable to perform those duties or exercise those
privileges.


If your friend can perform the duties of a pilot he should be ok.