Why can't I use "passer" to mean "come over" - 'ma mère voudrait que nous venions pour déjeuner'

Bonjour James,

"come over" is here going to be translated with "venir" as it involves a long-ish visit:

Viens déjeuner demain = come over for lunch tomorrow

"Passer" could be used but it involves a short stay:

il passe à la maison demain = he's coming over tomorrow

I hope this is helpful.

Bonne journée !