If you intend to breed the Apistogrammas, then yes it would be better to omit the tetras, to avoid stress for the female trying to defend the fry. Also in that case you should position the wood as MacZ suggested so that it makes more of a line of sight break across the middle (approx), so that the male and female can more easily avoid each other if or when necessary. The N. eques would probably be Ok with them.
On the other hand if you are not interested in breeding and want it as a display tank replicating the natural biotope as far as possible, then it would be better just to have the single male Apistogramma, then you could have both the tetras and the pencilfish without any problems.
On the other hand if you are not interested in breeding and want it as a display tank replicating the natural biotope as far as possible, then it would be better just to have the single male Apistogramma, then you could have both the tetras and the pencilfish without any problems.