The NT Gospel Doctrine manual does a good job of teaching this story and has some interesting questions for discussion (I think you could easily spend the entire lesson on this story, talking about the background of the Samaritans, the role of women in that time and place, the assumptions people make about this woman (both then and now), the kinds of questions she asks, how Jesus teaches her and the different levels of meaning in what he is saying, her reaction to his words, connections to other Biblical scenes at wells, the surprise of the disciples that Jesus was speaking to a woman, and so much more), but there is something else I think should be emphasized here in verse 42:
"They [Samaritans who listened to Jesus] said to the woman, ‘It is no longer because of what you said that we believe, for we have heard for ourselves, and we know that this is truly the Savior of the world.'"
We have a few standard missionary examples from the scriptures like Ammon and crew, but we need to tell other stories too. This is an excellent scripture to describe true conversion and what the goal of a missionary should be. It's not about the missionary and the gimmick or interesting tidbit they told you at the beginning; it's about the gospel of Jesus Christ. People came to Lamoni's court because Abish told them something amazing had happened, but that's not why they would have been converted. Lamoni listened to Ammon because of the arms, but that's not why he was converted. The Samaritans obviously had the advantage of being able to go directly to Jesus to hear what he had to say, but people today can still learn for themselves that Jesus truly is the Savior of the world and a missionary's job really isn't to convince people, but it's to show people where they can hear for themselves. John 4:42 is probably my favorite missionary scripture.
Also, Matthew describes a person who would have been viewed negatively (female, Samaritan, and married many times) but she is the person he uses to show us a good way to be a missionary.