Canada's Olympic silver medallist Marco Arop won the men's 800m in one minute and 43.69 seconds, ahead of American Nuguse (1:43.75) who also finished runner-up in the 1500m.
After his start to 2025 was disrupted by illness and injury, Olympic 1500m silver medallist Kerr showed he is returning to form by clocking a personal best 1:45.01 over two laps on Saturday.
Also on Saturday, American Olympic 100m bronze medallist Melissa Jefferson-Wooden pipped Olympic 200m champion Gabby Thomas to victory in the women's short sprints group.
Thomas ran a season's best 21.95 seconds to win her favoured event after finishing fourth in the 100m on Friday, but 100m winner Jefferson-Wooden produced a 200m personal best of 22.15 for third to win by one point.
Britain's Daryll Neita placed eighth in 22.93.
In the men's long sprints, Matthew Hudson-Smith ran 44.37 for third in the 400m, finishing fifth overall after placing seventh in the 200m.
The final day of Grand Slam Track action in Miami sees Britain's George Mills aim for victory in the men's long distance discipline as he races over 5,000m after his third-place finish in the 3,000m.
Zharnel Hughes races over 200m after placing fourth in the 100m, while in the women's long sprints group Amber Anning competes in the 200m.
There are two more three-day slams after Miami - in Philadelphia from 30 May and Los Angeles from 27 June.