Talon Stormwarden |
As far as I can see, Magic Missile isn't on the Witch's spell list. In that case no, you cannot use a wand of magic missile without a UMD check.
Do you mean that you found/bought a wand of magic missile as treasure and you have selected that wand as your bonded object? If that's the case, that doesn't magically put magic missile on your spell list. You would still need to make a UMD check to use the wand to cast magic missile.