What Yeshua called her is minor to the lessons on overcoming obstacles and being herself, he was teaching her... as well as us today.
She approached him in the way a Jew would: Have mercy on me, O Lord, thou Son of David... He ignored her at first and the disciples misread his actions as well. However she persisted. But he answered and said, I am not sent but unto the lost sheep of the house of Israel.
Then came she and worshipped him, saying, "Lord, help me".
Lesson 1: she gave up the pretense, worshipped him and just offer a simple prayer... "Lord, help me".
But he answered and said, It is not meet to take the children’s bread, and to cast it to dogs. And she said, Truth, Lord: yet the dogs eat of the crumbs which fall from their masters’ table.
Lesson2: She overcame the label others placed on her so she can access the Lord's table and receive his goodness just like anyone else. (read Psalm 24:1)
Then Jesus answered and said unto her, O woman, great is thy faith: be it unto thee even as thou wilt. And her daughter was made whole from that very hour.
The actions of this woman demonstrated her great faith. Even as James says: Even so faith, if it hath not works, is dead, being alone. Yea, a man may say, Thou hast faith, and I have works: shew me thy faith without thy works, and I will shew thee my faith by my works.
Yeshua came to save the world not condemn any part of it, these are, I believe, just two of the many lessons in this brief encounter.