This looks like threaded iron pipe screwed into the female ends of the stop cock - very tricky. You can just replace the inards if you can find an exact match - you may have trouble undoing the old one. Best if you can find a similar stop cock and dismantle it, then you'll know how it fits etc. Then just use the bits you need.
To replace the whole tap, you'll need undo a lot screwed iron pipes and work back to the tap - best not.
To replace the whole tap, you'll need undo a lot screwed iron pipes and work back to the tap - best not.