You cannot be immune to PvP but you can avoid.
You cannot stop people from attacking you but you can run away.
PvP happens mostly when someone else is grinding the same mob area as you or you have joined a guild that either actively PvP (which you will unlikely join) or is filled with kids that go around picking fights such that other guilds declare war on your guild.
For the more famous grinding spots, advisable to go with guild members.
For the usual day-to-day, no one will go and chop your head off for no reason.