A downhole well fluid assembly, comprising: a plurality of sliding sleeves having a central throughbore and disposed on a tubing string deployable in a wellbore; each of the sliding sleeves having a housing having an outer diameter, an inner diameter, a central throughbore, and first and second ports (60, 202), the first and second ports (60, 202) longitudinally offset from one another and communicating the central throughbore with the wellbore; each of the sliding sleeves having an insert and a retractable seat disposed in the central throughbore and being actuatable by a single ball deployable down the tubing string, the retractable seat being movable between a catch condition and a pass condition, the retractable seat in the pass condition being retracted into a slot of the central throughbore, the retractable seat in the catch condition being supported about its exterior diameter by the inner diameter of the housing; each of the inserts in the sliding sleeves being actuated by the single ball engaging the retractable seat in the catch condition and moving in a longitudinal direction from a closed condition to a first opened condition, the insert in the closed condition preventing fluid communication between the central throughbore and the wellbore through the first and second ports (60, 202), the insert in the first opened condition permitting first fluid communication between the central throughbore and the wellbore through the first port; each of the retractable seats in the sliding sleeves in the first opened condition being in the pass condition and allowing the single ball to pass therethrough; and each of the inserts in the sliding sleeves being further movable in an opposite longitudinal direction from the first opened condition to a second opened condition, the second opened condition permitting second fluid communication between the central throughbore and the wellbore through at least the second port. a plurality of sliding sleeves having a central throughbore and disposed on a tubing string deployable in a wellbore; each of the sliding sleeves having a housing having an outer diameter, an inner diameter, a central throughbore, and first and second ports (60, 202), the first and second ports (60, 202) longitudinally offset from one another and communicating the central throughbore with the wellbore; each of the sliding sleeves having an insert and a retractable seat disposed in the central throughbore and being actuatable by a single ball deployable down the tubing string, the retractable seat being movable between a catch condition and a pass condition, the retractable seat in the pass condition being retracted into a slot of the central throughbore, the retractable seat in the catch condition being supported about its exterior diameter by the inner diameter of the housing; each of the inserts in the sliding sleeves being actuated by the single ball engaging the retractable seat in the catch condition and moving in a longitudinal direction from a closed condition to a first opened condition, the insert in the closed condition preventing fluid communication between the central throughbore and the wellbore through the first and second ports (60, 202), the insert in the first opened condition permitting first fluid communication between the central throughbore and the wellbore through the first port; each of the retractable seats in the sliding sleeves in the first opened condition being in the pass condition and allowing the single ball to pass therethrough; and each of the inserts in the sliding sleeves being further movable in an opposite longitudinal direction from the first opened condition to a second opened condition, the second opened condition permitting second fluid communication between the central throughbore and the wellbore through at least the second port.