Court documents show the defendant initially gave the boy money and found out where he lived during the chance encounter.
On January 27, Wells rode his motorbike into the driveway of the Otahuhu property where he found the boy playing with his brother in the driveway.
Wells again gave the boy money and indecently assaulted him.
There was some dispute over the duration of the touching but Judge Andree Wiltens was unmoved.
"It does not really matter to me for how long ... you should not have been doing it full stop," he said.
Wells may have got away with the offending had it not been for two public health nurses who were sitting in a car nearby.
Without knowing any of the parties involved, they were worried enough to call authorities and charges were eventually laid.
Defence counsel John Clearwater said the encounter was brief and that there was no grooming involved but the judge disagreed, and despite the lawyer's resistance he added a year to the sentence because of the previous convictions.
Judge Andree Wiltens acknowledged Wells had undergone counselling in the past to address his inappropriate urges, but said it appeared "not to have achieved much".
"Here you are again on the same type of charges," he said.
Wells' daughter wrote a letter to the court in support of her father, praising the way he interacted with her kids.
"Your daughter's letters do you credit, but they do not affect my decision in any way," the judge said. "It does not reduce the seriousness of the offending."
Wells was jailed for two years and three months and was ordered to serve a minimum of 15 months.
"I'm still really concerned about other members of our community," Judge Andree Wiltens said.
Wells was deregistered as a teacher in 2011 after a hearing at the Teacher's Council Disciplinary Tribunal.
"In a case of this seriousness involving gross indecencies with a school aged child, it would be unrealistic to think that there is any other option but deregistration," it ruled.
Neither of the victims had been taught by Wells.