Divergent is a great novel to apply Maslow's hierarchy of needs to. Not only can the characters relate to the elements of the hierarchy of needs, but the ideals of their factions play into the hierarchy as well. It may be helpful for your thesis to think of the factions as more than a simple societal organization. Each one has its own culture and belief system which manifests in each of the characters.
Let's begin with Tris, the novel's protagonist. Raised in Abnegation, Tris was taught to live a modest and charitable life, refusing vanity and anything more than basic needs. Abnegation members eat simply, dress plainly, and even refuse to gaze at their own reflections. However, the novel's plot hits the ground running when Tris shocks her family and chooses to realign with Dauntless, her world's ragtag, tough, and flamboyant faction. What does this decision say about Tris? Is she seeking self-actualization, to develop her abilities and set goals for herself that Abnegation would not allow? Did she feel that Abnegation would not allow her to realize her full potential? Perhaps she felt as though she did not truly belong in Abnegation. Also, Tris is Divergent, so wouldn't it be better for her to stay hidden in Abnegation's quiet lifestyle? Keep these questions in mind as you analyze Tris and her choices.
Four is another major character, Divergent like Tris, and just as complex. He also chooses Dauntless despite being raised in Abnegation, and eventually rises to become a training instructor. Four is determined to be more than his faction; he wants to possess characteristics of all the factions. You could discuss this as a form of self-actualization: Four has set an ideal for who he wants to be as a person and is determined to realize it. He and Tris also seek friendship and intimacy with one another, forming a fierce bond between each other and the with the other members of Dauntless they trust.
I think it would be helpful for you to really delve into the ideals of the factions. The characters' faction choices play a huge part in who they want to be and indicates many psychological factors. You also have a plethora of characters to choose from: Tris, Four, Caleb, Natalie, and more. What do their faction choices say about who they are? What do they do in the factions, who do they trust? You have a lot to work with!