You can nominate your chosen beneficiary, or multiple beneficiaries. This could be a partner, friend, children, other relatives, a charity, a trust or a combination of a few different beneficiaries.
If you do not nominate beneficiaries, the money will go to any surviving financial dependents (i.e. your next of kin) and will usually only be available as a lump sum.
Nominations are not usually legally binding, but most pension providers will respect them unless there is a very good reason not to.