Yes you can! But it depends on what imbuement you want to put. In the example you gave about having 2 Life Leechs, a helmet cannot be imbued with it, so you'll need to imbue your armor and weapon.
Many knights use this set of imbuements: Weapon: Critical + Life Leech / Helmet: Mana Leech / Armor: Life Leech
PS: I gave an example of knights because it's the vocation I play, but you can search about the best set of Imbuements to your own vocation.