For a 2-week-old, wash all pump parts well with hot soapy water after every single use, since babies this young have less mature immunity and that washing matters most. Sterilizing once a day on top of that is enough for a healthy baby; you do not need to sterilize after every use.
Next Steps
Let the parts air dry fully before reassembling, wash your hands first, and keep the kit used only for your baby's milk.
Health Tips
If your baby was premature or has any health condition, ask your paediatrician whether more frequent sterilizing is advised.